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Date:   Thu, 10 Mar 2022 16:51:48 +0000
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Subject: Re: [PATCH v2] mailbox: tegra-hsp: Flush whole channel
Content-Language: en-US
To:     Thierry Reding <thierry.reding@gmail.com>,
        Jassi Brar <jassisinghbrar@gmail.com>
Cc:     linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220302150424.1305301-1-thierry.reding@gmail.com>
From:   Jon Hunter <jonathanh@nvidia.com>
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Hi Jassi,

On 02/03/2022 15:04, Thierry Reding wrote:
> From: Pekka Pessi <ppessi@nvidia.com>
> 
> The txdone can re-fill the mailbox. Keep polling the mailbox during the
> flush until all the messages have been delivered.
> 
> This fixes an issue with the Tegra Combined UART (TCU) where output can
> get truncated under high traffic load.
> 
> Signed-off-by: Pekka Pessi <ppessi@nvidia.com>
> Tested-by: Jon Hunter <jonathanh@nvidia.com>
> Fixes: 91b1b1c3da8a ("mailbox: tegra-hsp: Add support for shared mailboxes")
> Cc: stable@vger.kernel.org
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
> Changes in v2:
> - add Fixes: line
> - Cc stable
> 
>   drivers/mailbox/tegra-hsp.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/mailbox/tegra-hsp.c b/drivers/mailbox/tegra-hsp.c
> index acd0675da681..78f7265039c6 100644
> --- a/drivers/mailbox/tegra-hsp.c
> +++ b/drivers/mailbox/tegra-hsp.c
> @@ -412,6 +412,11 @@ static int tegra_hsp_mailbox_flush(struct mbox_chan *chan,
>   		value = tegra_hsp_channel_readl(ch, HSP_SM_SHRD_MBOX);
>   		if ((value & HSP_SM_SHRD_MBOX_FULL) == 0) {
>   			mbox_chan_txdone(chan, 0);
> +
> +			/* Wait until channel is empty */
> +			if (chan->active_req != NULL)
> +				continue;
> +
>   			return 0;
>   		}
>   


Any feedback on this? Can we queue this up for v5.18?

Thanks
Jon

-- 
nvpublic